Subsea capture system and method of using same

ABSTRACT

A subsea capture system, comprising a plurality of leak sources on a sea floor, the leak sources having a density less than sea water; and a plurality of capture devices located above each of the plurality of leak sources, the capture devices comprising a funnel shape comprising a large bottom opening inlet and tapering to a small top opening outlet

This application claims the benefit of U.S. Provisional Application No.61/378,243 filed Aug. 30, 2010, the entire disclosure of which is herebyincorporated by reference.

BACKGROUND

When oil and gas is spilled into the sea, for example from a leakingtanker ship, a leaking pipeline, from oil seeping from an undergroundformation, or from oil flowing from a subsea wellhead or blowoutpreventer, there is a desire to collect the oil and gas and contain andtransport or otherwise dispose of the oil and gas to preventenvironmental damage to the sea and nearby coastlines. Various systemsand methods of collecting spilled oil and gas are known in the art andset forth below:

U.S. Pat. No. 4,405,258 discloses a method for storing alighter-than-water fluid, e.g., oil, produced from the blowout of anoffshore subsea well. The method includes the steps of deploying acontainment dome in shallow water near the location of the seabed wherethe containment dome is to be located. The containment dome as an upperexpanded dome-like fluid impervious membrane, a fluid impervious hollowperipheral ring attached to the periphery of the membrane to provide adepending bag-like container, and discrete water drainage means withinthe bag-like container for connection to pump conduit means therefrom.Wet sand from the seabed is then pumped into the bag-like container, andwater is then drained from the wet sand through the water drainage meansso as to provide a body of drained sand disposed within the bag-likecontainer and providing a hollow peripheral ring as a hollow peripheraltorus acting as a self-supporting structure and as an anchor for thedome-like structural unit. The dome is then charged with a buoyantamount of air and the buoyed dome is floated out to the site where thedome is to be deployed. It is then submerged by controllably releasingthe air while substantially simultaneously filling the dome with water,thereby sinking the dome until the lighter-than-water fluid is capturedwithin the dome, while such fluid substantially simultaneously displaceswater from within the dome. U.S. Pat. No. 4,405,258 is hereinincorporated by reference in its entirety.

U.S. Pat. No. 4,643,612 discloses an oil storage barge having a concavebottom is adapted to be anchored over a subsea well or pipeline that isleaking oil. Flexible skirts extend to the ocean floor, and oil that istrapped under the barge may be stored in the barge or then transferredto another vessel. U.S. Pat. No. 4,643,612 is herein incorporated byreference in its entirety.

U.S. Pat. No. 5,114,273 discloses a protective device installed to oraround an offshore drilling platform for oil or gas and the device whenin operation to encircle or enclose the platform with a floatingcontainment device and attached oil containment curtain hanging from thedevice to the ocean floor. The pollution containment device to besubmerged normally and activated to the surface when needed. This devicewill entrap offshore platform pollutants in a short amount of time witha minimum amount of effort and will maintain a clean environment. Othermethods of offshore platform pollution containment devices are shown,including permanent non-moving oil pollution containment barriers andactivated barriers that operate internally and externally of the oilplatform to form an all encompassing barrier from the ocean floor toabove the water surface to hold an oil spill to the platform area. U.S.Pat. No. 5,114,273 is herein incorporated by reference in its entirety.

U.S. Pat. No. 5,213,444 discloses an oil/gas collector/separator forrecovery of oil leaking, for example, from an offshore or underwater oilwell. The separator is floated over the point of the leak and tetheredin place so as to receive oil/gas floating, or forced under pressure,toward the water surface from either a broken or leaking oil wellcasing, line, or sunken ship. The separator is provided with adownwardly extending skirt to contain the oil/gas which floats or isforced upward into a dome wherein the gas is separated from theoil/water, with the gas being flared (burned) at the top of the dome,and the oil is separated from water and pumped to a point of use. Sincethe density of oil is less than that of water it can be easily separatedfrom any water entering the dome. U.S. Pat. No. 5,213,444 is hereinincorporated by reference in its entirety.

U.S. Pat. No. 6,592,299 discloses a method of detecting and locatingfresh water springs at sea essentially by taking salinity measurementsand by methods and installations for collecting the fresh water. Thecollection installations comprise an immersed bell-shaped reservoircontaining and trapping the fresh water in its top portion, and apumping system for taking fresh water and delivering the fresh water viaa delivery pipe, characterized in that the circumference of the bottomend of the reservoir and/or the circumference of the bottom end of achimney inside the reservoir and open at its top end and surrounding thefresh water resurgence in part and preferably in full, follow(s) closelythe outline of the relief of the bottom of the sea so as to provideleakproofing between the circumference(s) and the bottom of the sea.U.S. Pat. No. 6,592,299 is herein incorporated by reference in itsentirety.

There is a need in the art for one or more of the following:

Improved systems and methods for collecting spilled oil and gas from amarine environment, for example collecting spilled oil and gas spillingfrom a number of locations;

Improved systems and methods for collecting oil and gas spilling frommultiple subsea wells;

Improved systems and methods for collecting oil and gas spilling from asubsurface formation located beneath a body of water; and/or

Improved systems and methods for collecting oil and gas spilling from asubsurface formation located beneath a body of water, and then burningthe gas and containing the oil in a surface vessel.

SUMMARY OF THE INVENTION

One aspect of the invention provides a subsea capture system, comprisinga plurality of leak sources on a sea floor, the leak sources having adensity less than sea water; and a plurality of capture devices locatedabove the plurality of leak sources, the capture devices comprising afunnel shape comprising a large bottom opening inlet and tapering to asmall top opening outlet.

Another aspect of the invention provides a method of capturing subsealeaks, comprising locating a plurality of leak sources on a sea floor,the leak sources having a density less than sea water; installing acapture device above each of the plurality of leak sources, the capturedevice comprising an opening at a bottom of the capture device toreceive the leak source within the capture device; and collecting theleak source at one or more collection points located at a top of thecapture device.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the features and advantages of the present invention can beunderstood in detail, a more particular description of the invention maybe had by reference to the embodiments thereof that are illustrated inthe appended drawings. These drawings are used to illustrate onlytypical embodiments of this invention, and are not to be consideredlimiting of its scope, for the invention may admit to other equallyeffective embodiments. The figures are not necessarily to scale andcertain features and certain views of the figures may be shownexaggerated in scale or in schematic in the interest of clarity andconciseness.

FIG. 1 is a schematic diagram depicting a wellsite positioned above asubsea reservoir, the wellsite having a containment system withfree-standing collectors in accordance with an aspect of the presentinvention.

FIGS. 2A-2B are schematic diagrams depicting a wellsite positioned abovea subsea reservoir, the wellsite having a containment system withanchored collectors in accordance with an aspect of the presentinvention.

FIG. 3 is a flow chart depicting a method of containment.

DETAILED DESCRIPTION

Some embodiments of the invention are shown in the above-identifiedfigures and described in detail below. Embodiments are described withreference to certain features and techniques for containing fluidsreleased into the sea.

FIG. 1:

FIG. 1 is a schematic diagram depicting a wellsite 100 positioned abovea reservoir 102. The wellsite 100 may be provided with a containmentsystem 103 for capturing fluids released or spilled into the sea 106.The wellsite 100 may have a surface system 104 floating on the sea 106,and a subsea system 105 therebelow. The subsea system 105 may recoverfluids from the reservoir 102, and pass such fluids to the surfacesystem 104.

The surface system 104 may be provided for collecting, distributingand/or processing the fluids retrieved from the subsea system 105 and/orthe reservoir 102. A riser 108 may extend below the surface system 104to a location proximate a sea floor (or mud line) 110. As shown in FIG.1, a subsea end of the riser 108 may be secured to a suction pile 111positioned in the sea floor (or mud line) 110. A riser connector 109 maybe provided to secure the riser 108 in position. In some cases, thesubsea end of the riser 108 may be positioned about the subsea system105 for receiving fluid therefrom, as will be described more fullyherein.

The subsea system 105 may have one or more blow-out preventers (BOP) 112positioned at a top end of one or more wellbores 114. The wellbore 114may extend through the sea floor 110 and into the reservoir 102. The BOP112 may be in fluid communication with the wellbore 114 for receivingthe fluids (e.g., gas, hydrocarbons, water, etc.) from the reservoir102. A manifold 116 may be fluidly connected between the BOP 112 and theriser 108 to facilitate and/or manipulate the flow of fluidstherebetween.

The riser 108 may receive fluids generated from the reservoir 102. Theriser 108 may be, for example, a tubular member for passing fluidreceived from the BOP 112 and/or manifold 116 to the surface system 104.A trap 117 may be provided at the subsea end of the riser 108 to collectfluids and/or solids. A pump 118 may be provided within the riser 108 toselectively draw fluid from the BOP 112 and into the riser 108.

Fluid may be passed from the riser 108 to the surface system 104. Thesurface system 104 may have a surface collector 122 for receiving thefluids. The surface collector 122 may be any suitable system forcollecting, storing, separating, and/or transporting the collectedfluids. The surface collector 122 may be, for example, a separator thatseparates the collected fluid into components, such as gas, water,liquid hydrocarbons and the like. The surface collector 122 may also bea conventional collector capable of storing fluid at or near thesurface.

The components of the fluid stored in the surface collector 122 mayoptionally be removed, for example, by burning gas with a flare 124, bytransporting liquids to a vessel 120 via tubing (or off-take line) 126and the like. The tubing 126 may be used to fluidly connect the surfacecollector 122 to the vessel 120. One or more surface collectors 122,risers 108, vessels 120 and tubings 126 may be provided.

In some embodiments, suitable collection funnels, risers, and separatorsthat may be used with the invention are disclosed in co-pending U.S.provisional patent applications 61/376,534, having attorney docketnumber TH4086; 61/376,542 having attorney docket number TH4085;61/376,595 having attorney docket number TH4088, which are all hereinincorporated by reference in their entirety.

From time to time, fluid from the reservoir 102 or a section of thewellbores 114 may escape into the sea 106. For example a wellsite leak130A from a wellbore 114A,B and/or from a BOP 112 may allow fluid toescape from the subsea system 105 and into the sea 106 as fluid isproduced from the reservoir 102. Further, a reservoir leak 130B, forexample fluids seeping through cracks or fissures in the sea floor 110,may allow fluid to escape directly from the reservoir 102 or a sectionof the well 114, through the sea floor 110 and into the sea 106. Thecontainment system 103 may be employed to recapture fluid released byone or more wellsite/reservoir leaks 130A and/or 130B. The containmentsystem 103 is preferably a mobile system that may be transported to thewellsite 100, and deployed into position to capture fluid from thewellsite/reservoir leaks 130A and/or 130B.

The containment system 103 may have one or more subsea (or leak)collectors 132 and one or more flow lines 134. One or more subseacollectors 132 may be positioned a distance above the wellsite/reservoirleaks 130A and/or 130B to collect fluids therefrom. The collected fluidmay travel from the subsea collector 132 to the surface collector 122via the flow lines 134. The flow lines may be fluidly connected directlyto the surface collector 122 and/or connected to the riser 108 for thefluids to flow to the surface collector 122 as shown in FIG. 1.

FIGS. 2A & 2B:

FIGS. 2A and 2B are schematic diagrams depicting various configurationsof a containment system 203 in operation at the wellsite 200. Thewellsite 200 has multiple wellbores 114A and 114B coupled to the BOPs112A, 112B (shown schematically) for producing the reservoir 102. Eachof the BOPs 112A, 112B may have produced a wellsite leak 130A. Areservoir leak 130B may also have been produced from the reservoir 102and through the sea floor 110. The wellbores 114A,B, BOPs 112A,B,reservoir 102, sea floor 110 and wellsite/reservoir leaks 130A,B may bethe same as those described with respect to FIG. 1, except that multiplewellsites 114A,B and BOPs 112A,B are provided.

The containment system 203 includes a surface system 204 and a subseasystem 205, similar to those of FIG. 1, except that fluid from thewellsite/reservoir leaks 130A,B are transferred from subsea collectors232 and to a riser 208 a by flow lines 134. Like the containment system103 of FIG. 1, fluid captured from the wellsite/reservoir leaks 130A,Bmay be passed to a conventional surface collector 122 for storage,separation and/or processing. The collected fluid may optionally bepassed to a vessel, such as vessel 120 of FIG. 1, for storage and/ortransport.

As shown in FIGS. 2A & 2B, the subsea collectors 132 are free-standing,or unsecured at a lower end thereof. Alternatively, collectors 132 maybe sealed and/or anchored to the BOP 112, or alternatively anchored tothe sea floor 110 such as with clump weights or driven or suction piles.

In the configuration of FIG. 2A, all of the subsea collectors 232 arefluidly connected to a riser 208 a by the flow lines 134. The subseacollectors 232 of FIG. 2A may be the same as the subsea collectors 132of FIG. 1. As shown in the Figure the subsea collectors 232 are anchoredto the subsea floor 110. These anchored subsea collector(s) 232 may beany suitable device for capturing fluid from the wellsite/reservoirleaks 130A and/or 130B. The subsea collectors 232 may be specificallydesigned and deployed for collecting fluid from a variety ofwellsite/reservoir leaks 130A and/or 130B.

As shown in FIG. 2A, the subsea collector 232 may include a non-sealedopen funnel (or water cap) 210 allowing free passage of fluid therein.The funnels 210 each have an open bottom 212, a cylindrical body 213, atapered top 214, and an exit end 215 configured to facilitate upwardmovement of the fluid into the flow lines 134. The open bottom 212 maybe large enough to capture, and/or enclose the fluids escaping from oneor more wellsite/reservoir leaks 130A and/or 130B. The exit end 215 ofthe funnel 210 may couple to the flow lines 134, using any suitablemethod. The funnel 210 may be constructed of any suitable material suchas metal, plastic, fabric, elastomer, a combination thereof, and thelike.

In other embodiments, the subsea collector 232 may include a sealedfunnel or flange connected directly to a BOP, or sealed around theperimeter of a well or a leak, for example with an annular suction pile.

As shown in FIG. 2A, the funnel 210 may be secured to the subsea floorby one or more clump weights (or anchors) 220 coupled to the funnel 210by one or more tethers 222. While the configurations of FIGS. 1 and2A-2B depict a subsea collector 232 having an open bottom 212 positioneda distance above a wellsite/reservoir leak 130A,B, the subsea collector232 may be positioned over wellsite equipment, such as the BOPs 112Aand/or 112B, to create a seal thereon and draw fluid therefrom. Inanother example, the funnels 210 may be forced into the mud or sea floor110 to create a seal therein, and to prevent release of fluid into thesea 106, or directly connected to an annular pile to create a sealaround the BOPs or leak sources.

The exit end 215 at the top of each of the subsea collector 232 isdepicted in FIG. 2A as being connected to corresponding flow lines 134.A valve 226 is optionally provided between the subsea collectors 232 andthe flow lines 134 to control the flow of the fluids from the subseacollectors 232 and into the flow lines 134. The flow lines 134 may beangled up from the subsea collectors 232, and toward the surface todefine an upward path for the flow of fluid therethrough. The flow lines134 may be any suitable flow path for allowing fluids to travel from thesubsea collectors 232 to the riser 208 a, and for supporting the subseacollectors 232 in position about the wellsite/reservoir leaks 130Aand/or 130B. For example, the flow lines 134 may be a flex hose, aplurality of pipes, a tubing, a canvass tube, a fabric tube, a metaltube, a composite tube, a plastic tube, a combination thereof, and thelike. Supports (not shown), such as buoys, may optionally be provided tosupport the subsea collectors.

The flow lines 134 may be assembled before, during and/or afterdeployment of the containment system 203 to the wellsite 200. The flowlines 134 and the subsea collector 232 may be deployed into position byan ROV, a diver, a submarine and/or other means (not shown). The flowlines 134 may further include any number of components, such as flanges,blinds, storage spools, connectors and the like, configured tofacilitate the routing, flexibility, operation, and/or transport of theriser 208 a and/or flow lines 134.

In an example where the flow lines 134 are flexible lines, such as flexhose, flexible tubing, and/or tubing, the flow lines 134 may be storedproximate the riser 208 a during transport, and extended into positionfor operation when desired. In an example where the flow lines 134 arehard pipes, the riser 203 may be provided with pre-drilled holes and/orconnectors, such as connector 221, for receiving the flow lines 134. Theriser 203 may also be pre-assembled and/or permanently piped with theflow lines 134 prior to installation. Any suitable method may be used tocouple the flow lines 134 to the riser 208 a, such as connectors,adhesives, bonds, welds and the like.

A surface end 202 of each of the flow lines 134 may be fluidly coupledto the riser 208 a as shown in FIG. 2A, or positioned inside riser 208 bas shown in FIG. 2B. The riser 208 a may be a conventional riser forpassing fluid to the surface collector 122. The riser 208 a may beadapted to receive the flow lines 134, for example from about 2 to about10 or more, such as 3 to 6 flow lines. Optionally, the riser 208 a maybe provided with openings, pipings, flanges or other features at variousdepths to facilitate receipt of the flow lines 134. Such features mayfacilitate the pre-assembly and/or installation of the containmentsystem 203 at the wellsite 200. The riser 203 may also be provided withvalves, pumps or other devices (not shown) to manipulate the flow offluid therethrough. For example, the riser 208 may have a valve (notshown) that may be activated to initiate the flow of fluid therethrough.

In the configuration of FIG. 2B, the containment system 203 has amodified riser 208 b. The riser 208 b of FIG. 2B may have an open bottom242 for receiving the upper end 202 of the flow lines 134. The flowlines 134 may be fluidly coupled to the riser 208 b by placing the flowlines 134 into the open bottom 242 of the riser 208 b. Any suitablemethod may be used to secure the flow lines 134 within the open bottom242 of the modified riser 208 b such as using connectors, adhesives,bonds, welds and the like.

FIGS. 1, 2A-2B depict specific configurations of containment systems103, 203. However, various combinations of the features described may beprovided. For example, the wellsites may be provided with one or morewellsite/reservoir leaks 130A, 130B and/or containment systems 103,203,BOPs 112A, 112B, manifolds 116, and/or other features as shown. One ormore valves (e.g., 226) may be positioned about the containment system203 to control the flow of the fluids captured by the subsea collector232. The one or more valves may be any suitable valves or combinationthereof for selectively controlling flow and/or pressure in thecontainment system, such as control valves, gate valves, check valves,and the like. For example, valve 226 may be a check valve configured toallow one way flow from the subsea collector 232 to the surfacecollector 122.

The subsea collector 232, riser 208 a,b and/or flow lines 134 may haveother devices for enhancing the operation thereof, such as one or morecollector valves 218 to control fluid flow, one or more pumps 223 tofacilitate movement of the fluid, one or more gauges 224 to take subseameasurements (e.g., temperature, pressure, flow rate, etc.), a manifold(e.g., 116 of FIG. 1) to manipulate fluid flow, and the like. Buoysand/or weights (not shown) may also be positioned about components ofthe wellsite, such as the flow lines 134, risers 208 a,b and/or subseacollectors 232, to control the location thereof.

FIG. 3:

FIG. 3 is a flow chart depicting a method 303 of containing one or moreleaks (e.g., wellsite/reservoir leaks 130A,B). The method involvespositioning (350) a containment system (e.g., 103, 203) about a leak ata wellsite (e.g., 100, 200). The step of positioning may involve, forexample, deploying (352) a surface collector (e.g., 122) to thewellsite, positioning (354) at least one subsea collector (e.g., 132,232) of the containment system over the leak, for example 2 or more,positioning (356) a riser (e.g., 108, 208 a,b) in fluid communicationwith the surface collector, fluidly connecting (358) the subseacollector(s) and the riser via at least one flow line (e.g., 134).

The method 303 further involves passing (360) fluid from the leak to thesurface collector via the containment system. The fluid may then beseparated (362) in the surface collector, and passed (364) from thesurface collector to a vessel. These steps may be performed in anyorder, and repeated as desired.

It will be understood from the foregoing description that variousmodifications and changes may be made in the preferred and alternativeembodiments of the present invention without departing from its truespirit. For example, one or more flow lines 134 may be used to fluidlyconnect one or more subsea collectors (e.g., 132, 232) to one or morerisers (e.g., 108, 208 a,b), surface collectors (e.g., 122) and/or otherdevices (e.g., vessel 120) for passing fluid thereto. The containmentsystems 103, 203 described herein may be free standing as shown in FIG.1, or anchored to the sea floor as shown in FIGS. 2A and 2B.

Illustrative Embodiments

In one embodiment, there is disclosed a subsea capture system,comprising a plurality of leak sources on a sea floor, the leak sourceshaving a density less than sea water; and a plurality of capture deviceslocated above the plurality of leak sources, the capture devicescomprising a funnel shape comprising a large bottom opening inlet andtapering to a small top opening outlet. In some embodiments, the leaksources comprise oil. In some embodiments, the leak sources comprisenatural gas. In some embodiments, each of the capture devices isconnected to a flow line. In some embodiments, each of the capturedevices is connected to a flow line, and each of the flow lines areconnected to a riser. In some embodiments, the plurality of leak sourcescomprise from about 3 to about 10 leak sources. In some embodiments, thecapture device comprises a major dimension across a base of the devicefrom about 0.5 meters to about 10 meters. In some embodiments, thecapture device comprises a diameter across a base of the device fromabout 1 meters to about 5 meters. In some embodiments, the capturedevice comprises a flexible sheet material. In some embodiments, atleast one capture device is fluidly sealed to a blow out preventer. Insome embodiments, the system also includes a separator fluidly connectedto the capture devices. In some embodiments, the system also includes aliquid storage vessel fluidly connected to the capture devices.

In one embodiment, there is disclosed a method of capturing subsealeaks, comprising locating a plurality of leak sources on a sea floor,the leak sources having a density less than sea water; installing acapture device above each of the plurality of leak sources, the capturedevice comprising an opening at a bottom of the capture device toreceive the leak source within the capture device; and collecting theleak source at a more collection points located at a top of the capturedevice.

This description is intended for purposes of illustration only andshould not be construed in a limiting sense. The scope of this inventionshould be determined only by the language of the claims that follow. Theterm “comprising” within the claims is intended to mean “including atleast” such that the recited listing of elements in a claim are an opengroup. “A,” “an” and other singular terms are intended to include theplural forms thereof unless specifically excluded.

We claim:
 1. A subsea capture system, comprising: a plurality of leaksources on a sea floor, the leak source fluids having a density lessthan sea water; and a plurality of capture devices located above theplurality of leak sources, the capture devices comprising a funnel shapecomprising a large bottom opening inlet and tapering to a small topopening outlet.
 2. The system of claim 1, wherein the leak sourcescomprise oil.
 3. The system of claim 1, wherein the leak sourcescomprise natural gas.
 4. The system of claim 1, wherein the leak sourcescomprise fluid from a hydrocarbon reservoir.
 5. The system of claim 1,wherein each of the capture devices is connected to a flow line.
 6. Thesystem of claim 1, wherein each of the capture devices is connected to aflow line, and each of the flow lines are connected to a riser.
 7. Thesystem of claim 1, wherein the plurality of leak sources comprise fromabout 3 to about 10 leak sources.
 8. The system of claim 1, wherein thecapture device comprises a major dimension across a base of the devicefrom about 0.5 meters to about 10 meters.
 9. The system of claim 1,wherein the capture device comprises a diameter across a base of thedevice from about 1 meters to about 5 meters.
 10. The system of claim 1,wherein the capture device comprises a flexible sheet material.
 11. Thesystem of claim 1, wherein at least one capture device is fluidly sealedor partially sealed to enclose a leak source.
 12. The system of claim 1,wherein at least one capture device is fluidly sealed to a blow outpreventer.
 13. The system of claim 1, further comprising a separatorfluidly connected to the capture devices.
 14. The system of claim 1,further comprising a liquid storage vessel fluidly connected to thecapture devices.
 15. A method of capturing subsea leaks, comprising:locating a plurality of leak sources on a sea floor, the leak sourcefluids having a density less than sea water; installing capture devicesabove the plurality of leak sources, the capture devices comprising anopening at a bottom of the capture device to receive the leak sourcewithin the capture device; and collecting the leak source at one or morecollection points located at a top of the capture devices.